Hybrid time and hardware redundancy to mitigate SEU effects on SRAM-FPGAs: Case study over the MicroLAN protocol

SRAM-based field programmable gate arrays (FPGAs) are particularly sensitive to single event upsets caused by high-energy space radiation. Single Event Upset (In order to successfully deploy the SRAM-FPGA based designs in aerospace applications, designers need to adopt suitable hardening techniques. In this paper, we describe novel hybrid time and hardware redundancy (HT&HR) structures to mitigate SEU effects on FPGA, especially digital circuits that are designed with bidirectional ports. The proposed structures that combine time and hardware redundancy decrease the SEU propagation mechanisms among the redundant hard units. Analysis results and fault injection experiments on some standard ISCAS benchmarks and MicroLAN protocol, as a case study over the bidirectional ports, show that the capability of tolerating SEU effects in HT&HR technique increases up to 70 times with respect to solely hardware redundant versions. On average, the proposed method provides 39.2 times improvement against single upset faults and 14.9 times for double upset faults; however it imposes about 14.7% area overhead. Also, for the considered benchmarks, HT&HR circuits become 8.8% faster on the average than their TMR versions.